2011CBET.2826....2P

J. L. Prieto, Princeton University, reports that a low-resolution optical spectrogram (range 370-920 nm; resolution 0.7 nm) of PSN J17524298+2904106 = SN 2011ft was obtained on Aug. 30.98 UT with the du Pont 2.5-m telescope (+ WFCCD) at Las Campanas Observatory in Chile. The spectrum shows broad He I absorption features consistent with a type-Ib supernova. Cross-correlation with a library of supernova spectra using SNID (Blondin and Tonry 2007, Ap.J. 666, 1024) shows that the spectrum is most similar to that of normal type-Ib supernovae at approximately 2-3 weeks after maximum light. The redshift derived from the supernova features is consistent within the uncertainties with the redshift of UGC 11021 (z = 0.0173; Springob et al. 2005, Ap.J. Suppl. 160, 149). It is interesting to note that the supernova is 60" from the center of its host galaxy, which implies a projected separation of about 22 kpc, assuming a distance of 75 Mpc to UGC 11021 (via NED, from the Virgo-infall recession velocity and h = 0.73). Furthermore, the spiral host galaxy (class type Sb in the RC3 catalogue) is seen almost edge-on, and the supernova lies well outside a linear extrapolation of the optical disk, at a projected distance from the disk of about 7 kpc. This location implies that the supernova either exploded in the halo of UGC 11021 or in a low-luminosity dwarf-galaxy companion. All these properties resemble the Ca-rich type-Ib supernova 2005E (Perets et al. 2010, Nature 465, 322), although 2011ft was two magnitudes brighter (absolute mag approximately -17) at discovery.